The present invention concerns an output control system which is capable of having a dot-type printer effectively output objects such as characters with a pitch which does not coincide with a multiple of the dot-width by an integer which said device either electrically or mechanically is inherently provided with.
A dot-type printer comprises a system to scan an object such as a printing paper in the lateral direction (which is generally referred to as a main scanning system) and a system to scan it in the vertical direction (which is generally referred to as a sub-scanning system) and outputs dots at an interval either mechanically or electrically predetermined so as to express a character or a diagram with assembled dots. The printer of above mentioned type has been put into practice as an output system for various data processing and data transmission systems such as the facsimile communication or the character communication.
As widely known, a facsimile communication is a system wherein the data to be transmitted such as manuscripts or original drawings are divided into predetermined picture elements, the system being particularly appropriate for transmitting drawings. A character communication is the system wherein a text consisting of characters alone is converted into codes by each character for transmission which are subsequently decoded back to characters on the receiving side.
There is no problem in the case such a dot-type printer is used as an output device separately for various individual communication systems such as the facsimile system, the character communication system, etc.
The intercommunication system between different communication terminals has become possible in recent years as data communication technology progressed; for example, characters can be outputted from a computer by a character communication to a facsimile receiver. Since the coding efficiency is predominantly higher in the character coding than the facsimile coding, there has been contemplated a composite communication system wherein the character data contained in a manuscript to be transmitted is coded by the character coding while the drawing data therein is coded by the facsimile coding for transmission.
In the cases of intercommunication or composite communication mentioned above, however, there is involved a basic problem in that a single dot-type printer has to cope with outputs of both character communication and facsimile communication. More specifically the problems can be summarized as below:
(1) The facsimile resolution is determined by CCITT (Internation Telegraph and Telephone Consultive Committee) at 8.04 pel. (picture element)/mm in the direction of main scanning while the linear density (number of lines) is determined at 7.7 lines/mm or 3.85 lines/mm in the direction of sub-scanning.
(2) As to characters, according to CCITT a pitch (a space allocated for a character) is set at either one of the multiples of 2.54 mm/character (1/10 inch/character) for the lateral direction and of 4.233 mm/line (1/6 inch/line) for the vertical direction by one of the integers of 0.5, 1, 1.5 or 2. For other characters including proportional spacing characters traditionally used, the intervals are determined at a multiple of 1/60 inch by an integer (by 2 to 8) in the lateral direction and at a multiple of 1/12 inch by an integer (by 1 to 4) in the vertical direction.
(3) As shown in Tables 1 and 2, the character pitches above mentioned do not coincide with the multiple of the dot-width by any one of the integers both in lateral and vertical directions of facsimile, deviating from the range.
(4) In prior art, pitches of characters were fixedly approximated to a multiple of the facsimile dot-width by an integer. That, however, causes errors; for instance, in the case where the character width of 1/10 inch (2.54 mm) is approximated to 20 pel against 20.41 pel of facsimile dot-width, the error of about 2% occurs in accumulation, shortening the print of 200 mm by 4 mm or 2 characters. The pitches are heretofore not in compliance with the recommendation of CCITT.
TABLE 1 ______________________________________ Character Width (inch) Number of Pels in Facsimile ______________________________________ 2/60 6.80 3/60 10.21 4/60 13.61 5/60 (1/12) 17.01 6/60 (1/10) 20.41 7/60 23.82 8/60 27.22 ______________________________________
TABLE 2 ______________________________________ Number of Scanning Lines in Facsimile Line Width (inch) (In the Case of 7.7 lines/mm) ______________________________________ 1/12 16.30 1/6 32.60 1/4 48.89 1/3 65.19 ______________________________________